Object-to-be-printed detector and print detecting method

ABSTRACT

The present invention relates to an apparatus for detecting an object-to-be-printed and aims at providing an apparatus for detecting an object-to-be-printed which is capable of discriminating whether the object-to-be-printed is plain paper or special paper. The apparatus includes an infrared sensor for detecting infrared rays  4  radiated by heating the object-to-be-printed  1  with heating means  2  and is capable of discriminating whether the object-to-be-printed is plain paper or special paper.

FIELD OF THE INVENTION

The present invention relates to apparatuses and methods for detectingobjects-to-be-printed.

BACKGROUND OF THE INVENTION

In association with the trend in recent years toward use of colorprinters and higher picture-quality printing, as theobjects-to-be-printed, paper of which the surface has been processedwith some coating, or special types of paper of which the base materialitself is special-purpose high-quality paper, glossy film,photographic-quality glossy film, photographic-quality glossy paper, OHPfilm, or back-printed film, etc., are being commercialized in additionto plain paper. As these special types of paper are expensive,development of means for discriminating them prior to printing theobject-to-be-printed has been sought for in order that an operator of acomputer and the like can avoid a situation of printing on a specialpiece of paper against the operator's will of printing on plain paper.

Previously, printing had been done by putting plain paper on one of twoor more trays loaded on a printer, for example, on an upper tray, andspecial paper on a lower tray, and the operator selecting in advancewhich tray to use prior to printing.

During this process, in the event a different type of paper was mixed ona predetermined tray, the operator suffered a problem of printing onwrong paper against the will.

The present invention addresses the above described previous problem andaims at providing an apparatus and method for detectingobjects-to-be-printed with which the object-to-be-printed can bedistinguished as to whether it is plain paper or special paper.

SUMMARY OF THE INVENTION

In order to achieve the above object, the present invention comprises anobject-to-be-printed, a heating means for heating theobject-to-be-printed, and an infrared sensor for detecting infrared raysradiated by the object-to-be-printed heated by the heating means.

The present invention provides an apparatus and method for detecting anobject-to-be-printed with which the object-to-be-printed can bedistinguished as to whether it is plain paper or special paper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an apparatus for detectingobjects-to-be-printed in a first exemplary embodiment of the presentinvention.

FIG. 2 is a cross-sectional view of an infrared sensor, being a key partof the apparatus for detecting objects-to-be-printed.

FIG. 3 is a graph illustrating spectral characteristic in terms of therelation between wavelength of infrared rays from plain paper heated bya heating means, being a key part of the apparatus for detectingobjects-to-be-printed, and the radiation rate.

FIG. 4 is a graph illustrating spectral characteristic in terms of therelation between wavelength of the infrared rays from special paperheated by the heating means, being a key part of the apparatus fordetecting objects-to-be-printed, and the radiation rate.

FIG. 5 is a perspective view of a paper transfer mechanism of abubble-jet printer to illustrate the embodiment.

FIG. 6 is a front view of a printing mechanism of a bubble-jet printerto illustrate the embodiment.

FIG. 7 is a cross-sectional view of an apparatus for detectingobjects-to-be-printed in a second exemplary embodiment of the presentinvention.

FIG. 8 is a cross-sectional view of an apparatus for detectingobjects-to-be-printed in a third exemplary embodiment of the presentinvention.

FIG. 9 is a front view of an apparatus for detectingobjects-to-be-printed in a fourth exemplary embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first aspect of the present invention comprises anobject-to-be-printed, a heating means for heating theobject-to-be-printed, and an infrared sensor for detecting the infraredrays radiated by the object-to-be-printed which is heated by the heatingmeans, and has an effect of discriminating the types ofobject-to-be-printed by detecting the difference in the amount ofinfrared rays radiated by the object-to-be-printed.

Also, a second aspect is one in which a filter for selectively passinginfrared rays is provided between the object-to-be-printed and theinfrared sensor of the first aspect. As it is capable of detecting thedifference in the spectral characteristic of the infrared rays radiatedby the object-to-be-printed, it has an effect of preciselydiscriminating the types of object-to-be-printed.

Also, a third aspect is one in which an optical chopper for interruptingor passing infrared rays from the object-to-be-printed is providedbetween the object-to-be-printed and the infrared sensor in the first orsecond aspect. As plural number of measurements is made possible byintermittently interrupting the infrared rays from theobject-to-be-printed thereby enabling detection of the difference in theamount of infrared rays with enhanced precision, it has an effect ofenabling discrimination of the types of object-to-be-printed withfurther enhanced precision.

Also, a fourth aspect is one in which a lens for collecting infraredrays is provided between the object-to-be-printed and the infraredsensor of any one of the first to the third aspects. As the focaldistance to be determined by the relation between the lens and theinfrared sensor can be shortened, the heating means can be downsized,thereby presenting an effect of enabling downsizing of the overallstructure.

A fifth aspect is an apparatus for detecting objects-to-be-printed asdescribed in the second aspect and provided with a filter as describedbelow. The filter is constituted of at least one of filters forselectively passing a wavelength band of 9.5 to 10.5 micrometer,selectively passing a wavelength band of 4.0 to 5.5 micrometer, orselectively passing a wavelength band of 2.5 to 3.5 micrometer. Beingprovided with this filter, it has an effect of enabling discriminationof the object-to-be-printed between plain paper and special paper withan enhanced precision.

A sixth aspect comprises an object-to-be-printed, a heating means forheating the object-to-be-printed, an infrared sensor for detecting theinfrared rays radiated by the object-to-be-printed heated by the heatingmeans, and a filter window integrally provided with the infrared sensorthat selectively passes the infrared rays. By sharing a filter and awindow, it has an effect of enabling downsizing at a low cost.

A seventh aspect is one in which an optical chopper for interrupting orpassing infrared rays is provided between the heating means and thefilter window of the sixth aspect. By intermittently interrupting theinfrared rays radiated by the object-to-be-printed, plural number ofmeasurements is made possible thereby enabling detection of thedifference in the amount of infrared rays with an enhanced precision. Asa result, it has an effect of enabling discrimination of the types ofobject-to-be-printed with further enhanced precision.

An eighth aspect is one in which a lens is provided between the heatingmeans and the filter window of the sixth or seventh aspect forcollecting infrared rays radiated by the object-to-be-printed heated bythe heating means. As the focal distance to be determined by therelation between the lens and the infrared sensor can be shortened, theheating means can be downsized, thus presenting an effect of enablingdownsizing of the overall structure as well.

A ninth aspect is an apparatus for detecting objects-to-be-printed asdescribed in the sixth aspect and provided with a filter window asdescribed below. The filter window is constituted of at least one offilter windows for selectively passing a wavelength band of 9.5 to 10.5micrometer, selectively passing a wavelength band of 4.0 to 5.5micrometer, or selectively passing a wavelength band of 2.5 to 3.5micrometer. Being provided with the filter window, it has an effect ofenabling discrimination of objects-to-be-printed between plain paper andspecial paper with an enhanced precision.

A tenth aspect comprises an object-to-be-printed, heating means forheating the object-to-be-printed, an infrared sensor for detecting theinfrared rays radiated by the object-to-be-printed heated by the heatingmeans, and a filter lens window integrated with the infrared sensor forcollecting as well as selectively passing the infrared rays. By sharinga filter, a lens and a window, it has an effect of enabling downsizingat a low cost.

Also, an eleventh aspect is an apparatus for detectingobjects-to-be-printed as described in the tenth aspect and provided witha filter lens window as described below. The filter lens window isconstituted of at least one of filter lens windows for selectivelypassing a wavelength band of 9.5 to 10.5 micrometer, selectively passinga wavelength band of 4.0 to 5.5 micrometer, or selectively passing awavelength band of 2.5 to 3.5 micrometer. Being provided with thisfilter lens window, it has an effect of enabling discrimination ofobjects-to-be-printed between plain paper and special paper with anenhanced precision.

Also, a twelfth aspect comprises an object-to-be-printed, a trapezoidaloptical plate provided on one of the sides of the object-to-be-printed,a heating means provided on one of the lateral sides of the opticalplate, and an infrared sensor provided on the other lateral side of theoptical plate. As it is capable of detecting difference in the spectralcharacteristic of the infrared rays reflected by theobject-to-be-printed, it has an effect of enabling discrimination of thetypes of object-to-be-printed with an enhanced precision.

Also, a thirteenth aspect is one in which a filter that selectivelypasses infrared rays is provided between the side of the optical plateopposite to the heating means and the infrared sensor of the twelfthaspect. As it is capable of detecting difference in the spectralcharacteristic of the infrared rays reflected by theobject-to-be-printed, it has an effect of enabling discrimination of thetypes of object-to-be-printed with an enhanced precision.

Also, a fourteenth aspect is one in which a lens for collecting infraredrays is provided between the side of the optical plate opposite to theheating means and the infrared sensor of the twelfth or thirteenthaspect. As the focal distance determined by the relation between thelens and the infrared sensor can be shortened, the heating means can bedownsized, thus presenting an effect of enabling downsizing of theoverall structure as well.

Also, a fifteenth aspect is one in which the infrared sensor in any oneof the first, sixth, tenth, and twelfth aspects is either pyroelectrictype or thermocouple type. As the sensitivity of detecting infrared raysdoes not depend on the wavelength of infrared rays, it has an effect ofenabling production of an output by using a filter for any band.

Also, a sixteenth aspect is one in which an object-to-be-printed isheated by a heating means and the infrared rays radiated by theobject-to-be-printed are detected while the object-to-be-printed is keptin contact with the heating means. It has an effect of enablingdiscrimination of the types of object-to-be-printed by stably detectingthe amount of difference in the infrared rays radiated by theobject-to-be-printed without being affected by the surroundings by beingkept in contact.

Also, a seventeenth aspect is one in which quality of paper isdiscriminated by detecting infrared rays having wavelength of 9.5 to10.5 micrometer or 4.0 to 5.5 micrometer or 2.5 to 3.5 micrometer asradiated by the object-to-be-printed described in the sixteenth aspect.It has an effect of enabling discrimination of object-to-be-printedbetween plain paper and special paper with an enhanced precision.

Also, an eighteenth aspect is one in which the amount of moisturecontained in paper can be measured by detecting infrared rays havingwavelength of 2.5 to 3.5 micrometer or 5.5 to 6.5 micrometer as radiatedby the object-to-be-printed described in the sixteenth aspect.

Also, a nineteenth aspect is one in which an object-to-be-printed isheated by a heating means and infrared rays radiated by theobject-to-be-printed is detected after separating theobject-to-be-printed from the heating means. It has an effect ofenabling discrimination of the difference in the thermal time constantsof the object-to-be-printed.

Also, a twentieth aspect is one in which thickness of paper is measuredby detecting the wavelength of infrared rays radiated by theobject-to-be-printed as described in the nineteenth aspect. It has aneffect of enabling discrimination with an enhanced precision as thedifference in the thermal time constants due to the difference in thethickness of the objects-to-be-printed is measured.

Operation of the apparatus for detecting objects-to-be-printed and themethod for detecting objects-to-be-printed as configured above will nowbe described.

To begin with, referring to drawings, an apparatus for detecting anobject-to-be-printed in the first exemplary embodiment of the presentinvention will be described.

FIG. 1 is a cross-sectional view of an apparatus for detecting anobject-to-be-printed in the first exemplary embodiment of the presentinvention.

In the drawing, an object-to-be-printed 1 is plain paper or specialpaper. A heating means 2, comprising a ceramic heater, halogen lamp, orthe like provided either in contact with or at some distance from thebottom surface of the object-to-be-printed 1, is heated to approximately160 to 180 degrees C. to heat the object-to-be-printed 1 toapproximately 80 degrees C. A lens 3 made of silicon, polyethylene, orthe like is provided above the object-to-be-printed 1 for collectinginfrared rays 4 radiated by the object-to-be-printed 1 heated by theheating means 2. A filter 5 comprising at least one of filters forselectively passing 9.5 to 10.5 micrometer wavelength band, selectivelypassing 4.0 to 5.5 micrometer wavelength band, or selectively passing2.5 to 3.5 micrometer wavelength band is provided above the lens 3.Also, between the filter 5 and the lens 3, an optical chopper 6 made ofstainless steel, iron-nickel steel, iron-nickel-cobalt steel, and thelike is provided for interrupting or passing the infrared rays 4. Aninfrared sensor 7 for detecting the infrared rays 4 that have passed theoptical chopper 6 is provided above the optical chopper 6.

The infrared sensor 7 is configured in the way illustrated in FIG. 2. InFIG. 2, a mount 11 has lead electrodes 12. An infrared ray detectingunit 13 consisting of a thin film or the like made by adding lanthanumto lead titanate, which has a function of absorbing infrared rays, andelectrically connected to the lead electrodes 12 is provided on the topsurface of the mount 11. A cylindrical sealing member 14 made of iron,Kovar, or the like is provided on the sides of the mount 11 in a mannersuch that it covers at least the infrared ray detecting unit 13. Thepyroelectric infrared sensor 7 is configured in such a way that aninfrared ray incident window 15 made of silicon, germanium, or the likeis provided to cover an opening of the sealing member 14. Althoughsurface charges always appear in the infrared sensor 7 due tospontaneous polarization, in the steady state in the atmosphere, itremains electrically neutral as the surface charges combine with chargesin the atmosphere. When infrared rays 4 enter the infrared sensor 7, thetemperature changes, causing a change in the neutral state of the chargeconditions. The amount of incident infrared rays is measured bydetecting the charges that appear during this change.

A description of the method of detection will now be given below on theapparatus for detecting an object-to-be-printed as configured above.

To begin with, the object-to-be-printed 1 is laid above the heatingmeans 2, and the object-to-be-printed 1 is heated up to about 80 degreesC. by heating the heating means 2 to about 160 degrees C. to 180 degreesC.

Subsequently, the infrared rays 4 collected by the lens 3 are led to thefilter 5 by opening the optical chopper 6. Normally, the optical chopper6 is closed to the filter 5 and is opened only when to detect theinfrared rays 4.

Next, the filter 5 allows only those infrared rays 4 to pass thatsatisfy the conditions of the filter 5 as described below.

Finally, the type of the object-to-be-printed 1 is identified bydetecting the amount of infrared rays that have passed the filter 5 andarrived at the infrared sensor 7.

Referring to drawings and taking plain paper and special paper asexamples of the object-to-be-printed, a description will be given in thefollowing on the spectral characteristic based on the relation betweenthe wavelength of the infrared rays radiated by the object-to-be-printed1 heated by the heating means 2 and the radiation rate.

FIG. 3 is a graph illustrating the spectral characteristic of plainpaper based on the relation between the wavelength of the infrared raysfrom the plain paper heated by the heating means, being an essentialpart of the apparatus for detecting an object-to-be-printed in the firstexemplary embodiment of the present invention, and the radiation rate.FIG. 4 is a graph illustrating the spectral characteristic of specialpaper based on the relation between the wavelength of the infrared raysfrom the special paper heated by the heating means, being an essentialpart of the apparatus for detecting an object-to-be-printed, and theradiation rate.

While the radiation rate of the plain paper shown in FIG. 3 is fromabout 60% to 85% in the wavelength passband of 9.5 to 10.5 micrometers,that of the special paper shown in FIG. 4 is from about 15% to 60%.Discrimination as to whether the paper is plain paper or special paperis made based on the difference in the radiation rates of the plainpaper and special paper. As has been described above, by using a filter5 having a wavelength passband of 9.5 to 10.5 micrometers, efficientdiscrimination between plain paper and special paper is enabled.

Also, while the radiation rate of the plain paper shown in FIG. 3 isfrom about 37% to 43% in the wavelength passband of 4.0 to 5.5micrometers, that of the special paper shown in FIG. 4 is from about 5%to 10%. In the same manner as above, discrimination as to whether thepaper is plain paper or special paper is made based on the difference inthe radiation rates of the plain paper and the special paper. As hasbeen described above, by using a filter 5 having a wavelength passbandof 4.0 to 5.5 micrometers, efficient discrimination between plain paperand special paper is enabled.

Also, while the radiation rate of the plain paper shown in FIG. 3 isfrom about 15% to 20% in the wavelength passband of 2.5 to 3.5micrometers, that of the special paper shown in FIG. 4 is from about 55%to 70%. In the same manner as above, discrimination as to whether thepaper is plain paper or special paper is made based on the difference inthe radiation rates of the plain paper and the special paper. As hasbeen described above, by using a filter 5 having a passband of 2.5 to3.5 micrometers, efficient discrimination between plain paper andspecial paper is enabled.

In this exemplary embodiment, although a description was made based on apyroelectric infrared sensor, a thermocouple type infrared sensor willalso do. A thermocouple type infrared sensor is suitable as it allowshigh precision measurement even when no chopper is available. Apyroelectric type infrared sensor is suitable as it allows highprecision measurement because five to ten times as high S/N ratio asthat of the thermocouple type is obtainable.

Also, though the configuration in this exemplary embodiment comprised alens, an optical chopper, and a filter, these may be selectivelycombined as required.

Also, when to use the apparatus for detecting an object-to-be-printed inproximity to the paper transport mechanism inside a bubble-jet printer,the heating means 2 may be disposed, as shown in FIG. 5, close to apaper feed roller 22 which is driven by a motor 21 to be used forfeeding paper so that infrared rays 4 from the object-to-be-printed 1may be collected with the lens 3 as the object-to-be-printed 1 passesabove the heating means 2, and detected by the infrared sensor 7 afterselectively passing through the filter 5. In this case, the lens 3 andthe filter 5 may be used upon selection if need be, and the opticalchopper 6 (not shown in the drawing) may be omitted by combining, as themotion of the object-to-be-printed 1 that passes the heating means 2, aforward motion in the direction of transport and a reverse motion in thedirection opposite to the direction of transport.

Also, when to use the apparatus for detecting an object-to-be-printed inproximity to the printing mechanism inside a bubble-jet printer, theinfrared sensor 7 may be integrally provided, as illustrated in FIG. 6,on a printing head (not shown in the drawing) which is moved by a belt31 when printing and on a printing carriage 32 which supplies ink (notshown in the drawing) to the printing head, and the heating means 2 maybe provided underneath the object-to-be-printed 1 so that infrared rays4 from the object-to-be-printed 1 can be collected by the lens 3 whenthe object-to-be-printed 1 passes above the heating means 2, selectivelypassed through the filter 5, and detected by the infrared sensor 7. Inthis case, the lens 3 and the filter 5 may be used upon selection ifneed be, and the optical chopper 6 (not shown in the drawing) may beomitted if the apparatus is so designed that infrared rays 4 can bedetected when the infrared sensor 7 moves above the heating means 2.

Next, referring to a drawing, a description will be given on anapparatus for detecting an object-to-be-printed in the second exemplaryembodiment of the present invention.

FIG. 7 is a cross-sectional view of the apparatus for detecting anobject-to-be-printed in the second exemplary embodiment of the presentinvention. Structural components which are identical as shown in FIG. 1explained in the first exemplary embodiment are indicated by the samereference numerals and detail description will be omitted.

A heating means 2 is provided underneath an object-to-be-printed 1 incontact with or apart from it. A lens 3 is provided above theobject-to-be-printed 1 for collecting infrared rays 4 radiated by theobject-to-be-printed 1 heated by the heating means 2. An optical chopper6 for interrupting or passing the infrared rays 4 is provided above thelens 3. A filter window 41 comprising at least one of filter windows forselectively passing a wavelength band of 9.5 to 10.5 micrometer,selectively passing a wavelength band of 4.0 to 5.5 micrometer, orselectively passing a wavelength band of 2.5 to 3.5 micrometer of theinfrared rays 4 passed by the optical chopper 6 is provided integrallywith the infrared sensor 7 for detecting the infrared rays 4.

By configuring the filter window 41 into an integral unit with theinfrared sensor 7, a filter and a window can be shared thus presentingan effect of enabling downsizing at a low cost.

In this exemplary embodiment, although the apparatus for detecting anobject-to-be-printed comprised a lens, an optical chopper and a filter,these may be used in selected combination as required.

Now, referring to a drawing, a description will be given on an apparatusfor detecting an object-to-be-printed in the third exemplary embodimentof the present invention.

FIG. 8 is a cross-sectional view of the apparatus for detecting anobject-to-be-printed in the third exemplary embodiment of the presentinvention. Structural components which are identical as in FIG. 1 in thefirst exemplary embodiment are indicated by the same reference numeralsand detail description will be omitted.

A heating means 2 is provided underneath an object-to-be-printed 1 incontact with or apart from it. An optical chopper 6 is provided abovethe object-to-be-printed 1 for interrupting or passing infrared rays 4radiated by the object-to-be-printed 1 heated by the heating means 2. Afilter lens window 51 for collecting the infrared rays 4 passed by theoptical chopper 6 and comprising at least one of filter lens windows forselectively passing a wavelength band of 9.5 to 10.5 micrometer,selectively passing a wavelength band of 4.0 to 5.5 micrometer, orselectively passing a wavelength band of 2.5 to 3.5 micrometer of theinfrared rays 4 passed by the optical chopper 6 is provided above theoptical chopper 6 integrally with the infrared sensor 7.

By configuring the filter lens window 51 into an integral unit with theinfrared sensor 7, a filter, a lens and a window can be shared thuspresenting an effect of downsizing at a low cost.

In this exemplary embodiment, although the apparatus for detecting anobject-to-be-printed comprised a lens, an optical chopper, and a filter,these may be used in selected combination as required.

Now, referring to a drawing, a description will be given on an apparatusfor detecting an object-to-be-printed in the fourth exemplary embodimentof the present invention.

FIG. 9 is a front view of an apparatus for detecting anobject-to-be-printed in the fourth exemplary embodiment of the presentinvention. Structural components which are identical as in FIG. 1 in thefirst exemplary embodiment are indicated by the same reference numeralsand detail description will be omitted.

A trapezoidal optical plate 61 made of silicon, germanium orchalcogenide materials such as zinc sulfur and the like, is provided onthe top surface of an object-to-be-printed 1. And the optical plate 61has, on its upper bottom surface which is in parallel to theobject-to-be-printed 1, a reflecting film 62 made of aluminum, gold,copper, or the like. Also, a heating means 2 is provided spaced apartfrom and perpendicular to one side of the optical plate 61 to supplyradiated infrared rays 4 into the optical plate 61. An optical chopper 6is provided spaced apart from and perpendicular to the other side of theoptical plate 61 for interrupting or passing infrared rays 4 radiated bythe heating means 2 and reflected sequentially in the order of theobject-to-be-printed 1, the reflecting film 62, and theobject-to-be-printed 1. A filter 5 comprising at least one of filtersfor selectiely passing a wavelength band of 9.5 to 10.5 micrometer,selectively passing a wavelength band of 4.0 to 5.5 micrometer, orselectively passing a wavelength band of 2.5 to 3.5 micrometer isprovided above the optical chopper 6. An infrared sensor 7 is providedabove the filter 5 for detecting infrared rays 4 that have passed theoptical chopper 6.

In this exemplary embodiment, although reference was made to the use ofa pyroelectric infrared sensor, a thermocouple type infrared sensor willalso do. A thermocouple type infrared sensor is suitable as it allowshigh precision measurement even when no chopper is in use. Apyroelectric type infrared sensor is suitable as it allows highprecision measurement because of five to ten times as high S/N ratio asthat of the thermocouple type.

In this exemplary embodiment, although the apparatus for detecting anobject-to-be-printed comprised a lens, an optical chopper and a filter,these may be used in selected combination as required.

Also, in the above described first to the fourth exemplary embodiments,quality of paper is discriminated by detecting infrared rays radiated bythe object-to-be-printed; however, quantity of moisture in theobject-to-be-printed such as paper can be measured by using similarapparatus.

In this case, the infrared rays radiated by the object-to-be-printed are2.5 to 3.5 micrometer or 5 to 6.5 micrometer in wavelength, which areradiation bands of water. When compared with a dry object-to-be-printed,a moist object-to-be-printed shows greater amount of radiation in eachof the above bands. In other words, radiation corresponding to thequantity of moisture in the object-to-be-printed is made, and, bydetecting the amount of radiation, the quantity of moisture of theobject-to-be-printed can be measured.

A description of an apparatus for detecting an object-to-be-printed inthe fifth exemplary embodiment of the present invention will be given inthe following.

To begin with, an object-to-be-printed is laid on a heating means, andthe heating means is separated from the object-to-be-printed after ithas been heated up to about 80 degree C. by heating the heating means toabout 160 to 180 degree C.

Subsequently, infrared rays radiated by the heated object-to-be-printedis collected with a lens if necessary.

Next, the infrared rays collected by the lens are transferred to afilter by opening the optical chopper if necessary. Normally, theoptical chopper is closed to the filter and is opened only when todetect infrared rays.

Finally, the quantity of infrared rays that have passed the filter andarrived at an infrared sensor is detected to measure thickness of theobject-to-be-printed.

In this case, when the change of sensor output is measured from themoment the heating means is separated, the rate of change is differentdepending on the thickness of the object-to-be-printed. Namely, as thethickness increases, the rate of change decreases, or the thermal timeconstant increases. By detecting the difference in the thermal timeconstants, it is possible to measure the thickness of theobject-to-be-printed. Here, change in the output was measured afterheating the object-to-be-printed and then separating the heating means;however, it goes without saying that similar effect can be obtained bymeasuring the change of output from the moment the object-to-be-printedis brought into intimate contact with or close to the heating means.

The apparatus for detecting an object-to-be-printed and the method fordetecting an object-to-be-printed in the first to the fifth exemplaryembodiments can be used in printers. It goes without saying that theprinters include ink-jet printers, laser printers, and copying machines.

INDUSTRIAL APPLICATION

As has been described above, the present invention has an effect ofproviding an apparatus for detecting an object-to-be-printed which iscapable of discriminating whether the object-to-be-printed is plainpaper or special paper.

What is claimed is:
 1. An apparatus for detecting anobject-to-be-printed comprising an object-to-be-printed, heating meansfor heating the object-to-be-printed, and an infrared sensor fordetecting infrared rays radiated by the object-to-be-printed heated bythe heating means, wherein said apparatus determines the type of objectbeing heated based on the presence or absence of said radiated infraredrays within a predefined frequency band.
 2. The apparatus for detectingan object-to-be-printed of claim 1, wherein a filter that selectivelypasses infrared rays is provided between the object-to-be-printed andthe infrared sensor.
 3. The apparatus for detecting anobject-to-be-printed of claim 2, wherein the filter comprises at leastone of a filter that selectively passes 9.5 to 10.5 micrometerwavelength band, a filter that selectively passes 4.0 to 5.5 micrometerwavelength band, and a filter that selectively passes 2.5 to 3.5micrometer wavelength band.
 4. The apparatus for detecting anobject-to-be-printed of claim 2, wherein an optical chopper thatinterrupts or passes infrared rays from the object-to-be-printed isprovided between the object-to-be-printed and the infrared sensor. 5.The apparatus for detecting an object-to-be-printed of claim 2, whereina lens for collecting infrared rays is provided between theobject-to-be-printed and the infrared sensor.
 6. The apparatus fordetecting an object-to-be-printed of claim 1, wherein an optical chopperthat interrupts or passes infrared rays from the object-to-be-printed isprovided between the object-to-be-printed and the infrared sensor. 7.The apparatus for detecting an object-to-be-printed of claim 6, whereina lens for collecting infrared rays is provided between theobject-to-be-printed and the infrared sensor.
 8. The apparatus fordetecting an object-to-be-printed of claim 1, wherein a lens forcollecting infrared rays is provided between the object-to-be-printedand the infrared sensor.
 9. An apparatus for detecting anobject-to-be-printed of claim 1, wherein the infrared sensor is ofeither pyroelectric type or thermocouple type.
 10. An apparatus fordetecting an object-to-be-printed comprising an object-to-be-printed,heating means for heating the object-to-be-printed, an infrared sensorfor detecting infrared rays radiated by the object-to-be-printed heatedby the heating means, and a filter window which is integrated with theinfrared sensor and which selectively passes the infrared rays, whereinsaid apparatus determines the type of object being heated based on thepresence or absence of said radiated infrared rays within a predefinedfrequency band.
 11. The apparatus for detecting an object-to-be-printedof claim 10, wherein an optical chopper for interrupting or passinginfrared rays is provided between the heating means and the filterwindow.
 12. The apparatus for detecting an object-to-be-printed of claim11, wherein a lens for collecting infrared rays radiated by theobject-to-be-printed heated by the heating means is provided between thethe heating means and the filter window.
 13. The apparatus for detectingan object-to-be-printed of claim 10, wherein a lens for collectinginfrared rays radiated by the object-to-be-printed heated by the heatingmeans is provided between the heating means and the filter window. 14.The apparatus for detecting an object-to-be-printed of claim 10, whereinthe filter window comprises at least one of a filter window thatselectively passes 9.5 to 10.5 micrometer wavelength band, a filterwindow that selectively passes 4.0 to 5.5 micrometer wavelength band,and a filter window that selectively passes 2.5 to 3.5 micrometerwavelength band.
 15. An apparatus for detecting an object-to-be-printedof claim 10, wherein the infrared sensor,is of either pyroelectric typeor thermocouple type.
 16. An apparatus for detecting anobject-to-be-printed comprising an object-to-be-printed, heating meansfor heating the object-to-be-printed, an infrared sensor for detectinginfrared rays radiated by the object-to-be-printed heated by the heatingmeans, and a filter lens window integrated with the infrared sensor forcollecting and selectively passing the infrared rays, wherein saidapparatus determines the type of object being heated based on thepresence or absence of said radiated infrared rays within a predefinedfrequency band.
 17. The apparatus for detecting an object-to-be-printedof claim 16, wherein the filter lens window comprises at least one of afilter lens window that selectively passes 9.5 to 10.5 micrometerwavelength band, a filter lens window that selectively passes 4.0 to 5.5micrometer wavelength band, and a filter lens window that selectivelypasses 2.5 to 3.5 micrometer wavelength band.
 18. An apparatus fordetecting an object-to-be-printed of claim 16, wherein the infraredsensor is of either pyroelectric type or thermocouple type.
 19. Anapparatus for detecting an object-to-be-printed comprising anobject-to-be-printed, a trapezoidal optical plate provided on one of thesurfaces of the object-to-be-printed, heating means provided on one sideof the optical plate, and an infrared sensor provided on the other sideof the optical plate.
 20. An apparatus for detecting anobject-to-be-printed of claim 19, wherein a filter for selectivelypassing infrared rays is provided between the side of the optical plateopposite to the heating means and the infrared sensor.
 21. An apparatusfor detecting an object-to-be-printed of claim 20, wherein a lens forcollecting infrared rays is provided between the side of the opticalplate opposite to the heating means and the infrared sensor.
 22. Anapparatus for detecting an object-to-be-printed of claim 19, wherein alens for collecting infrared rays is provided between the side of theoptical plate opposite to the heating means and the infrared sensor. 23.An apparatus for detecting an object-to-be-printed of claim 19, whereinthe infrared sensor is of either pyroelectric type or thermocouple type.24. A method for detecting an object-to-be-printed by heating theobject-to-be-printed with heating means and detecting infrared raysradiated by the object-to-be-printed with the object-to-be-printed madein contact with the heating means, wherein said method determines thetype of object being heated based on the presence or absence of saidradiated infrared rays within a predefined frequency band.
 25. Themethod for detecting an object-to-be-printed of claim 24, wherein paperquality is discriminated by detecting infrared rays having wavelength ofany of 9.5 to 10.5 micrometer, 4.0 to 5.5 micrometer, or 2.5 to 3.5micrometer radiated by the object-to-be-printed.
 26. The method fordetecting an object-to-be-printed of claim 24, wherein the amount ofmoisture contained in the paper is measured by detecting infrared rayshaving wavelength of either 2.5 to 3.5 micrometer or 5.5 to 6.5micrometer radiated by the object-to-be-printed.
 27. A method fordetecting an object-to-be-printed by heating the object-to-be-printedwith heating means and detecting the infrared rays radiated by theobject-to-be-printed after the object-to-be-printed is separated fromthe heating means, wherein said method determines the type of objectbeing heated based on the presence or absence of said radiated infraredrays within a predefined frequency band.
 28. The method for detecting anobject-to-be-printed of claim 27, wherein thickness of paper is measuredby detecting wavelength of infrared rays radiated by theobject-to-be-printed.